WASHINGTON -- Deep international fissures and a split among victims' families helped push the United States and Britain into abandoning their hard line on how to bring the Libyans accused of plotting the 1988 Pan Am Flight 103 bombing to justice.

Officials in Washington and London confirmed last week that after years of insisting that two Libyan intelligence agents be tried in the United Kingdom or the United States, the two countries were exploring a third option: trial in the Netherlands under Scottish law and using Scottish judges.

They described the shift as a creative way of calling Libya's bluff and finally obtaining justice for the families of the 259 passengers and 11 people on the ground who perished after the U.S. jumbo jet exploded in the skies over Lockerbie, Scotland, on Dec. 21, 1988.

But pressure had been building for months to get the two governments to adopt a new course -- both from some of the victims' families and from other countries.

The two suspects, Abdel Basset Ali Mohmen al-Megrahi and Al Amin Khalifa Fhimah, were indicted in November 1991, nearly three years aftera bombing that the U.S. and British governments said was Libyan state-inspired.

"This was a Libyan government operation from start to finish," State Department spokesman Richard Boucher said at the time.

British Foreign Secretary Douglas Hurd said: "This was a mass murder which is alleged to involve the organs of government of a state."

When Libya refused to hand over the suspects, the United States and Britain successfully lobbied the United Nations Security Council to impose a ban on air travel to and from Libya and on arms sales to its regime, and cut Libya's diplomatic presence abroad. The sanctions were tightened in 1993 to include a freeze on some Libyan assets and a ban on the sale of oil technology.

Facing opposition from Libya's fuel customers in Europe, the two countries shrank from trying to impose the harshest punishment, an oil embargo.

'A leaky tool'

What there was of an embargo has proved "a leaky tool," according to Lori Fisler Damrosch, an international law professor at Columbia University.

"Inevitably, the longer the sanctions go on, the more porous they become," she said.

The most serious threats to the sanctions have come from Libya's neighbors and allies in Africa and in the Arab world.

Meeting in Burkina Faso in June, the Organization of African Unity urged its members to ignore the U.N. sanctions if they affected humanitarian or religious matters or involved OAU business.

Members also appealed to the United States and Britain to relax the sanctions imposed in 1993.

State Department spokesman James P. Rubin bitterly rebuked the OAU for what he called a shortsighted action that "constitutes a direct assault on the authority of the Security Council and its binding resolutions."

The United States softened its position when Libyan leader Col. Muammar el Kadafi's hospitalization for hip surgery this month gave Egyptian President Hosni Mubarak a chance to fly to Tripoli, Libya, with a medical team.

Mubarak, whose country is a close U.S. ally and a major aid recipient, made the trip after getting no objection from the U.N. committee that decides whether to grant exceptions to sanctions. As he sat next to Kadafi, he told reporters that Arabs "are one nation and these borders are illusionary."

The presidents of Chad, Niger, and Burkina Faso openly breached the sanctions, flying into Libya without obtaining U.N. approval.

The Arab League had urged its members to take steps to ease the travel embargo imposed on Libya.

An important political blow against the United States and Britain came in criticism from South African President Nelson Mandela, who is universally regarded as a man of integrity.

Mandela, who remains loyal to countries such as Libya and Cuba, which supported his African National Congress' long campaign against apartheid, spoke out in October during a British Commonwealth conference in Edinburgh, Scotland.

"I have never thought in dealing with this question that it is correct for any particular country to be the complainant, the prosecutor and the judge," he said.

As long ago as 1994, a group of families of British victims of the Flight 103 bombing had despaired of ever getting justice under the demands put forward by the United States and Britain.

While most American families backed the government's insistence on a trial in the United States or Britain, the British families adopted the proposal of a Scottish legal scholar, Robert Black, for a trial in the Netherlands under Scottish law and with an international panel of judges.

A spokesman for the group, Dr. Jim Swire, won Kadafi's endorsement of the idea during a visit to Libya last spring. Swire lost his 23-year-old daughter, Flora, in the crash.

Discussions had been under way for months between the United States and Britain, including talks between President Clinton and British Prime Minister Tony Blair "on more than one occasion," according to a British official.